The present invention generally relates to breathing assistance devices.
More precisely, the invention concerns a breathing assistance device for a patient, comprising:                A source of respiratory pressurised gas,        A breathing connection to allow the patient to receive said gas,        At least one sensor for acquiring a parameter representative of the operation of the device.        
Devices of this type are already known.
FIG. 1 therefore diagrammatically illustrates an example 10 of a known device.
The device 10 comprises a fixed console 100.
This fixed console 100 comprises among others a source of pressurised gas 105.
In practice, this gas source can be in the form of a ventilator or a fan (the term ventilator is retained in the text hereinbelow for convenience).
The ventilator is mounted fixed inside the console.
The fixed console 100 also generally comprises a central unit for controlling the operation of the device.
Such a central unit is connected to one or more sensors of parameter(s) representative of the operation of the device (typically the gas flow rate and the gas pressure), and it controls the operation of the device as a function of this/these parameter(s).
The console comprises means for interfacing with a user (who can be the patient himself).
These means are illustrated schematically here in the form of a screen 101 and control/adjustment buttons 102.
The respiratory gas is conveyed from the source 105 to the patient via a conduit 110, whereof a first end is connected to said source.
The second end of the conduit 110 will be generally designated in this text by the term “breathing connection”.
More generally still, a <<breathing connection >> designates in this text the interface between the device and the patent.
Such a <<breathing connection >> can correspond to a breathing mask, as illustrated in the illustration in FIG. 1.
It is specified that it is also envisageable to utilise a device of this type in so-called intrusive  mode, where the patient is then intubated with this second end.
In this latter case, the <<breathing connection >> corresponds simply to the end of the conduit with which the patient is intubated.
In the example illustrated in FIG. 1, the mask 120 comprises vents 121 for arranging leaks of respiratory gas. These leaks especially allow a part of the CO2 rejected by the patient to be evacuated during expiration phases.
The elements described hereinabove in reference to FIG. 1 are found in a large number of known devices.
These devices provide substantial assistance.
They are nonetheless associated with certain disadvantages, and certain limitations. Certain of these disadvantages/limitations will be explained hereinbelow.
First of all, the general configuration of such devices generally leads to fairly significant space requirements (due to the presence of the fixed console, the conduit connecting the console and the patient, possibly other conduits such as an expiration conduit.).
This space requirement can constitute a disadvantage per se.
In addition, this general configuration also gives rise to constraints for the patient.
In particular, the patient must remain attached to the fixed console, by way of the conduit.
This naturally limits the movements of the patient, and can constitute an inconvenience (especially at night, within the scope for example of sleep apnoea treatment).
Furthermore, in such a general configuration, even if a certain proportion of the CO2 expirated by the patient can escape via the vents of the mask, the remaining proportion of CO2 is <<trapped >> in the conduit, where it is forced back during expiration.
A <<plug >> of CO2 is thus formed in the conduit. And pollutants such as for example germs expirated by the patient can be found in this <<plug >>.
This plug of CO2 can thus constitute pollution for the patient, who can possibly be induced to inspire a part of the CO2 and germs expirated previously.
This plug of CO2 can also constitute pollution for the device, where it is capable of migrating or being pushed towards elements of the device such as the gas source located at the end of the conduit 110.
The presence of CO2 and its possible pollutants in such elements of the device can even constitute a danger for the patient.
In fact, in the case where CO2 and/or pollutants would be present in such elements of the device, the device would risk conveying this CO2 and/or these pollutants to the patient.
This can constitute a danger for the patient (especially in the case of hypercapnic patients).
It is thus necessary in this case to proceed with disassembling and cleaning these elements. This constitutes a fastidious operation, which also makes the device unavailable.
It will also be noted that even by abstracting the specific problem of pollution which has just been explained à propos CO2 trapped in a conduit, patients are exposed to the disadvantages associated with cleaning operations mentioned hereinabove.
Therefore, the known devices are exposed to these disadvantages, which are considered particular causes of pollution (associated or not with the conduit), or not.
It is thus necessary from time to time to proceed with disassembling and cleaning the ventilator, which, as explained, constitutes a fastidious operation, and which also has the disadvantage of making the device unavailable.
With respect to the aspects associated specifically with the general configuration comprising a console and a conduit, it is also to be noted that the presence of the conduit causes losses of charge and pneumatic inertia:                which diminish the energetic yield of the device,        and which increase the complexity of the control of the device, where these losses of charge and inertia must be integrated into the control programs of the device.        
This disadvantage is naturally all the more sensitive than the conduit is long.
Furthermore, limitations and disadvantages are associated specifically with the presence of the mask vents.
And in certain applications (especially in the case of a device functioning in BPAP or CPAP mode), the known devices generally utilised take on the configuration illustrated FIG. 1, which comprises a mask with vents.
It is specified that the CPAP type (acronym of the English term Continuous Positive Airway Pressure—this type also able to be designated in French by the acronym PPC for Pression Positive Continue [Continuous Positive Pressure]) designates the devices at a single pressure level.
In these devices, the speed of rotation of the ventilator is regulated by measuring the pressure exerted on the single conduit of the device (conduit 110 in FIG. 1).
The unique control pressure is generally fixed at a value less than 20 mbars (this value is expressed in surpressure relative to atmospheric pressure), which limits the use of such devices to the treatment of light pathologies.
The devices of BPAP type (acronym of the English term Bilevel Positive Airway Pressure, this acronym being a registered trade mark—and this type also able to be designated in French by the acronym VNDP for Ventilation Nasale à Deux niveaux de Pression [Nasal Ventilation at two Pressure Levels]) has the same general architecture, but functions with two control pressures (a value of inspiration pressure and a value of expiration pressure).
The devices mentioned hereinabove referring to FIG. 1 (in particular operating in BPAP or CPAP mode) therefore often comprise masks with vents.
Such a mask with vents can cause unwanted effects.
In particular, the gas outlets associated to the vents can be directed towards parts of the body of the patient, and cause phenomena such as desiccation of these parts of the body.
This is a disadvantage, especially when such consequences are observed in the eyes of the patient.
In addition, leaks must be taken into consideration for administering the operation of the device (for example consideration of these leaks in the programs of the central unit which administers this operation).
This naturally tends to increase the complexity of the device.
It thus appears that certain disadvantages and limitations are linked to the known devices described hereinabove.
The aim of the invention is to eliminate these disadvantages.